Formation mechanism of yolk-shell LaMnO3 microspheres prepared by P123-template and oxidation of NO

摘要

The yolk-shell LaMnO3 perovskite microspheres were fabricated by a novel,simple and mild soft template approach.A series of template-P123 concentrations(0-6.12 mmol·L^-1)were employed to optimize the most complete spheres.When the concentration of P123 is 3.0 mmol·L^-1,the obtained yolk-shell microspheres with a diameter of 200-700 nm were constructed by nanoparticles.The possible formation mechanism of the yolk-shell microspheres was revealed step by step via XRD,SEM,TEM,EDS and HRTEM.Molecules of P123 were suitably mixed with solvents for double shelled vesicles through self-assembly,which interacted with metal complexes to form P123-metal vesicles.After the removal of P123 and citric acid by calcination at 700 ℃,the yolk-shell LaMnO3 microspheres with through-channels were obtained.Through-channels on the surface were due to citric acid and the solid core was attributed to the shrink of inner vesicles.Prepared yolk-shell microsphere samples possessed a larger surface area and a higher maximum NO conversion value of 78% at 314 ℃ for NO oxidation,compared with samples without the yolk-shell structure.